An organic EL (Electroluminescence) display device is represented as an example of a display device. An organic EL display device has an organic light-emitting element (hereinafter, referred to a light-emitting element) in each of a plurality of pixels formed over a substrate. A light-emitting element has a layer including an organic compound between a pair of electrodes and is operated by supplying current between the pair of electrodes. Since a light-emitting element is formed as an all-solid type display element, no change occurs in a gap between the substrates even if the substrates are provided with flexibility and folded or bent. Thus, bending and folding a display device does not influence display quality in principle. This feature has been utilized to manufacture a so-called flexible display (sheet display) in which a light-emitting element is fabricated over a flexible substrate. For example, Japanese patent application publication No. 2011-8937 discloses an organic EL display device having flexibility and a structure member for heat radiation arranged on an outer surface of a substrate.